<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>
    <input type="text" value="1" id="ipt">
    <select id="sel">
        <option value="a">a</option>
        <option value="b">b</option>
    </select>
    <script type="text/javascript" src="./jquery.js"></script>
    <script>
        // 触发change事件需通过失去焦点或者回车（非IE）才会，通过DOM改变值不会触发
        $("#ipt").on("change",function(){
            console.log("ipt-change");
            $("#sel").val("c")
        })
        // 触发条件：选择并值改变
         $("#sel").on("change",function(){
            console.log("sel-change")
        }) 
    </script>
</body>
</html>